Why won't the array fit my curve?
Couple of things to make it work.


Origins of the objects should be in the the Center of the Mass and in the same place in space for both of them.


Ctrl+Alt+Shift+C > Origin to Center of Mass (Volume)
Shift+S > Cursor to Center
Shift+S > Selection to Cursor



  Repeat for both objects.


This way we will have both objects in the center of the scene with Origin 
Points in the sam place, like so: 


Add Array then Curve modifier and set it like this: